In many receivers that are configured to operate in present systems, the receiver must be arranged to determine when a signal of interest is present. One technique that is used in many system or system protocols in order to facilitate this determination is the transmission of known data that a receiver can hunt for and when found decide that data is present. The known data may be provided as a preamble in a data frame. When the preamble is “found”, it is presumed that a data frame is available. Conventional receivers normally correlate received data with known data and when received data is found that correlates well with the known data, a detect is declared. Known systems are subject to errors both positive and negative, i.e., declaring a detect when the received data in fact did not include the known data and not declaring a detect when the known data in fact was present. While safeguards in terms of other processing are normally used to mitigate these errors, such safeguards may consume processing capacity or result in lower system capacities due to unnecessary repeated transmissions.
Other factors in receivers, such as offset correction and gain control exacerbate the problems of making accurate determinations of whether known data is available. For example, during early portions of received data the systems that are correcting for any offset (typically referred to as DC offset) and establishing appropriate signal levels by setting various receivers gains, can corrupt the received data in one or more manners, thereby contributing to errors in the detection process.
The duration of the known data can be increased and an improvement in detect accuracy could be realized, however this is not a popular choice since the known data is overhead and increases in overhead may result in lower system capacity.